An allograft includes bone, tendon, or other types of tissue that is transplanted from one person to another. Allografts are used in a variety of medical treatments, such as knee replacements, bone grafts, spinal fusions, eye surgery, and skin grafts for the severely burned. Allografts come from voluntarily donated human tissue obtained from donor-derived, living-related, or living-unrelated donors and can help patients regain mobility, restore function, enjoy a better quality of life, and even save lives in the case of cardiovascular tissue or skin.
Allograft processing centers are generally responsible for processing and cataloging allografts collected by organ procurement organizations (“OPOs”). The OPOs are, in turn, responsible for collecting and/or recovering voluntarily donated tissues and gathering any pertinent medical information about those tissues before transferring them to the processing center.
Once an allograft is received, the allograft processing center is then responsible for processing the allograft and readying it for safe and effective medical use. Such processing may involve several steps including inspection, testing, cleansing, and cataloging, all subject to strict standards and regulations.
When allografts involve tendon tissue, processing centers are often called upon by surgeons performing the tissue transplants to provide allografts with measured and identified (i.e., labeled) diameters. Specifically, when a surgeon transplants tendon tissue, it is helpful for the surgeon to know the diameter of the tendon being transplanted in order to customize a proper fit for the patient. In many cases, a surgeon may require a specific diameter for a specific patient, application, or area of the body.
Generally, the standard for measuring non-bone tendons is by means of threading or forcing the tissue through a standard “sizing block,” which provides a fixed template having a number of graduated tubes in varying diameters. An exemplary sizing block of the type that exists in the prior art is shown in FIG. 1. To use a sizing block, a technician forces tendon tissue through the graduated tube that most closely approximates the diameter of the tendon to be measured and then associates the diameter of the selected tube with the diameter of the tendon. Other existing measurement devices require numerous discrete measurements along the length of an article to measured, using a cinching device that must be clamped or torqued by the user.
These existing approaches exhibit several inherent deficiencies. First, they rely on an individual user's strength and subjective judgement regarding how much force to apply during measurement. In the case of a sizing block, larger applied forces can allow a tendon to fit through a smaller measurement tube that might be unobtainable with a lesser force. Other discrete clamping or torqueing-type measurement devices rely on the user to clamp the device around the article to be measured, subjecting the measurement to variances in how hard the user can or will press.
Measurements are also skewed by the tendon's natural moisture content. Tendons exhibit semi-solid, rather than solid, properties, and moisture content differs from tendon to tendon. Differing moisture contents alter the natural lubrication of the measurement device, allowing for smoother or rougher movement of the tendon through the sizing block or other device. Tendons with higher moisture contents liberally lubricate the measurement device and slide more easily through smaller holes, while tendons with lower moisture contents experience more friction and may be perceived as larger in diameter because they resist movement.
Because existing measurement devices do not extend along the full length or even a substantial portion of a tendon, they require several discrete measurements over the length of the tendon, as well as follow-up calculations to obtain an average thickness or diameter. This “multiple measurement” method introduces additional time, steps, and variables into the process and produces a less accurate result. Also, by measuring a tendon's length at different points using a discrete ring or tube, the tendon is allowed to bulge at the edges of the device. Material that should be accounted for in the measurement is forced outward, skewing the end result.